#include <iostream>
#include <functional>
#include<cstdio>
using namespace std;
const string s = "+-*/%";
int MyMath(int x,int y,char op)
    {
        int result = 0;
        switch (op)
        {
        case '+':
            result = x + y;
            break;
        case '-':
            result = x - y;
            break;
        case '*':
            result = x * y;
            break;
        case '/':
        {
            if (y == 0)
            {
                cerr << "除0错误" << endl;
                result = -1;
                break;
            }
            result = x / y;
            break;
        }
        case '%':
            if (y == 0)
            {
                cerr << "除0错误" << endl;
                result = -1;
                break;
            }
            result = x % y;
            break;
        default:
            break;
        }
        return result;
    }

class Task
{
public:
    using func_t = function<int(int, int,char)>;
    Task(int x, int y ,char op,func_t func):_func(func),_x(x),_y(y),_op(op)
    {}
    Task()
    {}
    string operator()()
    {
        int result = _func(_x, _y,_op);
        char buffer[1024];
        snprintf(buffer,sizeof buffer,"%d %c %d = %d",_x,_op,_y,result);
        return buffer;
    }
    string toTaskString()
    {
        char buffer[1024];
        snprintf(buffer,sizeof buffer,"%d %c %d = ?",_x,_op,_y);
        return buffer;
    }

private:
    int _x;
    int _y;
    char _op;
    func_t _func;
};
